The present invention is directed to a hollow drill bit formed out of a tubularly-shaped support member with cutter elements arranged at the leading end of the support member with the elements projecting radially outwardly beyond the outer surface of the support member.
Hollow drill bits of the above type are disclosed in DE-GM No. 8 515 322 and are used specially for cutting holes of large diameter in rock, concrete, masonry or the like. The cutter members are provided with abrasive cutting particles, particularly synthetic diamonds.
The drilling operation is carried out mostly along with a simultaneous supply of a cooling liquid. The supply of cooling liquid is effected at a more or less high pressure and mostly from the inside of the tubularly-shaped support member, whereby an outflow is assured along the outer side of the member carrying off drillings or drill chips. In actual practice, however, it is not always possible to provide a sufficiently high pressure for the cooling liquid for removing drill chips, particularly when using mobile drilling equipment.